The average price of a gallon of diesel dropped more than 4 cents over the past week, according to figures from the U.S. Department of Energy.

The DOE's Energy Information Administration's figures put the national average Monday at $2.98 per gallon. This is the third week in a row the price has dropped. The highest average price was reported in the Central Atlantic region at $3.121; the lowest price in the Gulf Coast region at $2.936.

This price is still 62.8 cents higher per gallon than a year ago.

Crude oil, meanwhile settled at $72.58 a barrel on the New York Mercantile Exchange Tuesday, down $1.39, or 1.9 percent, from Friday's close. Weak manufacturing data from China and weakness in the euro versus the dollar helped keep oil prices down, despite positive signals in the U.S. economy that otherwise might push up prices based on anticipated increases in demand.

The U.S. Institute of Supply Management purchasing manager's index fell to 59.7 in May from 60.4 in April -- indicating growth, albeit slower -- but that was a full point better than the market had expected. In addition, construction spending rose 2.7 percent in April, the largest gain in nearly 10 years.